AO Series 4 illuminator cleaning tips?
AO Series 4 illuminator cleaning tips?
I recently acquired a nice AO Series 4. I've spent a few hours with it now and I'm seeing a lot of dust and crud in the field of view. I started by cleaning my eyepieces, got them reasonably clean, but there's still a considerable amount of dust somewhere. I took the collector lens out of the base and cleaned it and noticed while it was out that the mirror and the lens behind the iris diaphragm are quite dirty. They are not easy to reach from above. I tried blowing away the dust with a puffer, but it is either stuck on, or on the other side of the glass. I don't want to just start taking everything apart willy nilly. Can anyone describe a minimally invasive procedure to get at these parts to clean them well? Thanks!
Re: AO Series 4 illuminator cleaning tips?
Just one small tip for any microscope mirror (I am not familiar with Leitz scopes): Clean it by blowing air, try to avoid touching it with anything other than air.
Re: AO Series 4 illuminator cleaning tips?
I know first surface mirrors are delicate, and one should avoid touching them if possible. I have had to clean the mirrors on a couple Newtonian telescopes and have been able to do it with dish soap without causing any overt damage. Is the coating on the flat in the illuminator likely to be more delicate than the coating on, for instance, a 30-40 year old Newtonian primary mirror?
If I can clean it without touching it I will, but initial attempts with a puffer were not promising.
If I can clean it without touching it I will, but initial attempts with a puffer were not promising.
Re: AO Series 4 illuminator cleaning tips?
When I had my series 4, I took apart the base assembly and the mirror came off from its spring-loaded support (old glue no longer worked). The mirror surface was not that delicate, if I remember correctly. So I glued back the mirror. Not too difficult.
But one has to pay attention to aligning all the optical centers and proper Kohler, during reassembly.
Wait for Apochronaut to confirm this though. As it has been a year or two and I may not remember it exactly.
But one has to pay attention to aligning all the optical centers and proper Kohler, during reassembly.
Wait for Apochronaut to confirm this though. As it has been a year or two and I may not remember it exactly.
Last edited by zzffnn on Thu Feb 08, 2018 4:09 am, edited 1 time in total.
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
Typed this in , while you were sending , Fan.
Dirty, eh? I am a bit surprised. The listing said " fully functional". From my perspective that should mean clean. It is always good to sell a clean microscope, unless advising the buyer otherwise.
o.k. so, best thing is to make it right. In this case familiarity does not breed contempt. Cleaning a microscope is the best way to get to know it's functions well and you have the added benefit of making it better during the honeymoon.
Illuminator: I have done a cleaning with out removing anything but it is very hard to do the mirror well, and get to the underside of the illuminator aperture window/lens. It can be removed from above but you will need a pin spanner with a fairly broad span and narrow pins.
Remove the microscope head and turn the microscope on it's side on a clean cloth , old t-shirt or tight weave t-towel.....white is best. Remove the light shield by removing the two slot head screws.
The entire illuminator relay system is mounted to a cast aluminum flange that is mounted from the bottom up on the lower side of the base with 3, 3/32" hex screws. The flange is circular and surrounds the illuminator aperture window in the base. The mirror floats below that on two springs and a third toe extension floats in a tiny yoke. Back off the two mirror adjustors on the top of the base, to relieve as much spring tension as possible. By lifting the two spring ends out of their seats, the mirror relaxes and the third corner will slide out of the ring. If you don't have a spring hook or similar tool, a small allen key works well to lift the spring ends out , and to replace them. You can also make a lifter out of stout or braided , high tensile thread, such as linen or koratron or some thin wire. Remove the mirror.
You can now easily remove the 3 3/32" hex screws, lift off the relay lens and iris diaphragm unit. The unit separates with another 3, 3/32" hex screws and all surfaces can then be easily cleaned. Be careful not to lose that little yoke washer that the toe of the mirror frame goes through. You would probably have to fabricate a replacement.
Take special care with the mirror. If it is really dusty, I usually flood the surface with the cleaning solution and then lightly drag a tissue across it to collect the liquid and as much suspended dust as is possible. A couple of repeats may be necessary to be sure any abrasive material is gone. Final cleaning and polishing is done with swabs and very lightly, with as much liquid as is necessary. Sometimes a light scratch may occur, or maybe was already there. It isn't worth worrying about. The effect on the illumination beam will be negligible.
Check the cement on the mirror. Over the years it can get a bit brittle. It wouldn't hurt at this point to touch it up with some epoxy. A wooden pointed skewer makes a good applicator, just to fill in the odd crack , if necessary. You wouldn't need any more than a 1/4" diameter blob of the mixed resin , to do the job.
The three key areas where crud in the visual field is found are 1) eyepieces. determined , if the crud turns with the eyepiece. Usually it is on the bottom lens with the # 146 eyepieces. Clean the lower surface meticulously and if necessary, pop out the bottom lens to get at the upper surface of the bottom lens.
2) the windows, down in the ocular tubes. The ocular tubes unthread counter clockwise easily , so getting at those windows is easy.
3) the compensating lens. this lens can be unscrewed in order to clean both the upper and lower surface. dirt on it, doesn't show up in the field sharply but it can lower the contrast.
4) for the trinocular, it is always advisable to remove the tube and clean the prism down in there.
Other than that , a cleaning of the prisms in the head might be advised but hopefully not necessary.
Dirty, eh? I am a bit surprised. The listing said " fully functional". From my perspective that should mean clean. It is always good to sell a clean microscope, unless advising the buyer otherwise.
o.k. so, best thing is to make it right. In this case familiarity does not breed contempt. Cleaning a microscope is the best way to get to know it's functions well and you have the added benefit of making it better during the honeymoon.
Illuminator: I have done a cleaning with out removing anything but it is very hard to do the mirror well, and get to the underside of the illuminator aperture window/lens. It can be removed from above but you will need a pin spanner with a fairly broad span and narrow pins.
Remove the microscope head and turn the microscope on it's side on a clean cloth , old t-shirt or tight weave t-towel.....white is best. Remove the light shield by removing the two slot head screws.
The entire illuminator relay system is mounted to a cast aluminum flange that is mounted from the bottom up on the lower side of the base with 3, 3/32" hex screws. The flange is circular and surrounds the illuminator aperture window in the base. The mirror floats below that on two springs and a third toe extension floats in a tiny yoke. Back off the two mirror adjustors on the top of the base, to relieve as much spring tension as possible. By lifting the two spring ends out of their seats, the mirror relaxes and the third corner will slide out of the ring. If you don't have a spring hook or similar tool, a small allen key works well to lift the spring ends out , and to replace them. You can also make a lifter out of stout or braided , high tensile thread, such as linen or koratron or some thin wire. Remove the mirror.
You can now easily remove the 3 3/32" hex screws, lift off the relay lens and iris diaphragm unit. The unit separates with another 3, 3/32" hex screws and all surfaces can then be easily cleaned. Be careful not to lose that little yoke washer that the toe of the mirror frame goes through. You would probably have to fabricate a replacement.
Take special care with the mirror. If it is really dusty, I usually flood the surface with the cleaning solution and then lightly drag a tissue across it to collect the liquid and as much suspended dust as is possible. A couple of repeats may be necessary to be sure any abrasive material is gone. Final cleaning and polishing is done with swabs and very lightly, with as much liquid as is necessary. Sometimes a light scratch may occur, or maybe was already there. It isn't worth worrying about. The effect on the illumination beam will be negligible.
Check the cement on the mirror. Over the years it can get a bit brittle. It wouldn't hurt at this point to touch it up with some epoxy. A wooden pointed skewer makes a good applicator, just to fill in the odd crack , if necessary. You wouldn't need any more than a 1/4" diameter blob of the mixed resin , to do the job.
The three key areas where crud in the visual field is found are 1) eyepieces. determined , if the crud turns with the eyepiece. Usually it is on the bottom lens with the # 146 eyepieces. Clean the lower surface meticulously and if necessary, pop out the bottom lens to get at the upper surface of the bottom lens.
2) the windows, down in the ocular tubes. The ocular tubes unthread counter clockwise easily , so getting at those windows is easy.
3) the compensating lens. this lens can be unscrewed in order to clean both the upper and lower surface. dirt on it, doesn't show up in the field sharply but it can lower the contrast.
4) for the trinocular, it is always advisable to remove the tube and clean the prism down in there.
Other than that , a cleaning of the prisms in the head might be advised but hopefully not necessary.
Re: AO Series 4 illuminator cleaning tips?
Thanks all! Apo, that seems pretty straightforward. The window on the illuminator iris wasn't on your list of most likely sources of junk in the field. Is that because dirt there doesn't show up in the field, or because dirt is more common elsewhere? Most of the artifacts I'm seeing come in and out of focus as I adjust the condenser and they are in a plane that is close to that of the illuminator iris. In other words, when I have Kohler set up properly, they are not sharply in focus, but they are still pretty obvious in the field of view, and they do come in to focus with very slight adjustment of the condenser.
I will check the other surfaces you mentioned. Cleaning the field lenses of the eyepieces helped a great deal, but there's definitely a good bit of dust left to find.
I have another question about centering the lamp and aligning the mirror. While I had the collector lens out, I tried to look at how the lamp centering mechanism worked. I imagine the process would be to close the illuminator iris down then adjust the lamp centering screws until the spot of light is centered in the flat diagonal mirror. I couldn't find a way to get a good look at the mirror with the stage in the way, though. Is the only way to get a straight-on look at this by removing the entire upper assembly from the base? Would I be able to focus on the mirror from above using a centering telescope? I have a CT at work that I can borrow.
One more possibly related question; when I am setting up Kohler illumination, when I close the illuminator iris, (I think this is just with the low power and the 10x objectives) I see three distinct images of the illuminator iris. One larger one in the center and two additional smaller images arranged vertically, one above and one below the primary image. When I close the iris again, they all converge to a single centered image. Is this normal? Caused by internal reflections in the illuminator or condenser? It's not something I recall ever seeing in the scopes I use at work.
I will check the other surfaces you mentioned. Cleaning the field lenses of the eyepieces helped a great deal, but there's definitely a good bit of dust left to find.
I have another question about centering the lamp and aligning the mirror. While I had the collector lens out, I tried to look at how the lamp centering mechanism worked. I imagine the process would be to close the illuminator iris down then adjust the lamp centering screws until the spot of light is centered in the flat diagonal mirror. I couldn't find a way to get a good look at the mirror with the stage in the way, though. Is the only way to get a straight-on look at this by removing the entire upper assembly from the base? Would I be able to focus on the mirror from above using a centering telescope? I have a CT at work that I can borrow.
One more possibly related question; when I am setting up Kohler illumination, when I close the illuminator iris, (I think this is just with the low power and the 10x objectives) I see three distinct images of the illuminator iris. One larger one in the center and two additional smaller images arranged vertically, one above and one below the primary image. When I close the iris again, they all converge to a single centered image. Is this normal? Caused by internal reflections in the illuminator or condenser? It's not something I recall ever seeing in the scopes I use at work.
Re: AO Series 4 illuminator cleaning tips?
Oh... and has anyone used the inexpensive Neewer adjustable lens spanner that's available on Amazon? Does it work well? Are the blades thin enough for notches in small retaining rings?
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
I have never bought anything from Amazon but the item is probably widely available elsewhere. I have used a couple of inexpensive ones, I bought on ebay. If you send a link; it might be a familiar one to me and I could comment.
Setting up the illuminator on a series 4. There are three adjustments which affect the centering of the illumination beam, 1 of which also affects the focus of an element in the image plane and another 1 which affects the focus of th image plane only. 4 adjustments in all.
1) The condenser focus. 2) the mirror plane adjusters(2). 3) The condenser centering adjusters(2), if fitted. 4) The filament centering adjusters (2).
The one thing that you did not get with that microscope is the centering condenser mount cat. # 244. You got the simpler version cat.# 243. Having a centering condenser mount, makes adjusting the illuminator a lot easier, if it has been badly disturbed.
The first thing you need to determine , is whether the mirror is plane with the field iris. Place the 10X objective over the stage and swing the aux. condenser lens out. Establish Köhler. Is the border of the field iris in equal focus all around? If not you will need to adjust the mirror adjustors, in order to get the mirror in perfect planarity with the field iris. The image of the field iris will move around but with the correct adjustment, you should be able to keep it fairly central.
Next, open the field iris so you can just see it in focus inside the perimeter of the field. Close the condenser iris. They should be concentric. If not, you should be able to readjust the mirror , to obtain concentricity with the condenser iris, as well as maintaining planarity with the field iris. If not, you may have to lower the condenser, slacken the two screws that fasten it's fork and adjust the condenser centering, some.
Lastly, when everything is centered and levelled, with Köhler established and the illuminator on full, adjust the bulb with the two illuminator adjusting screws to get the brightest possible field.
Additionally, the aux. condenser lens has an adjustable stop. It may need trimming.
The presence of two ghost images in the field when you establish Köhler , is normal with that illumination system.
Setting up the illuminator on a series 4. There are three adjustments which affect the centering of the illumination beam, 1 of which also affects the focus of an element in the image plane and another 1 which affects the focus of th image plane only. 4 adjustments in all.
1) The condenser focus. 2) the mirror plane adjusters(2). 3) The condenser centering adjusters(2), if fitted. 4) The filament centering adjusters (2).
The one thing that you did not get with that microscope is the centering condenser mount cat. # 244. You got the simpler version cat.# 243. Having a centering condenser mount, makes adjusting the illuminator a lot easier, if it has been badly disturbed.
The first thing you need to determine , is whether the mirror is plane with the field iris. Place the 10X objective over the stage and swing the aux. condenser lens out. Establish Köhler. Is the border of the field iris in equal focus all around? If not you will need to adjust the mirror adjustors, in order to get the mirror in perfect planarity with the field iris. The image of the field iris will move around but with the correct adjustment, you should be able to keep it fairly central.
Next, open the field iris so you can just see it in focus inside the perimeter of the field. Close the condenser iris. They should be concentric. If not, you should be able to readjust the mirror , to obtain concentricity with the condenser iris, as well as maintaining planarity with the field iris. If not, you may have to lower the condenser, slacken the two screws that fasten it's fork and adjust the condenser centering, some.
Lastly, when everything is centered and levelled, with Köhler established and the illuminator on full, adjust the bulb with the two illuminator adjusting screws to get the brightest possible field.
Additionally, the aux. condenser lens has an adjustable stop. It may need trimming.
The presence of two ghost images in the field when you establish Köhler , is normal with that illumination system.
Re: AO Series 4 illuminator cleaning tips?
Maybe I'm doing something wrong, but I can't see the field iris and the condenser iris in focus simultaneously to check that they are concentric?
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
My mistake. You will need to rack the condenser down a little in order to get the condenser in enough focus to see it's positioning and then back a bit to get the field iris, as well. You won't get them in sharp focus together but you can determine their relative positions in this way. Using a bertrand lens with an objective removed gets them both in focus and you can more easily see the alignment of the nosepiece too.
Re: AO Series 4 illuminator cleaning tips?
Thanks for the clarification. Haven't been able to do the test yet or any additional cleaning. I'll report back when I have.
Re: AO Series 4 illuminator cleaning tips?
Yes.. I have a spanner such as that.... It works great.. Just be careful it does not slip..clengman wrote:This is the lens spanner I was looking at.
https://rover.ebay.com/rover/0/0/0?mpre ... 1303732469
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
The concern I have with that one is that it has a single rail, rather than a double rail. Some old lenses, especially where aluminum bodies are used can be unbelievably tight. I could see that wrench twisting, if sufficient pressure were applied. A double rail wrench will twist less, I think. It does look like they have considered that in it's design by using a reasonably thick flat bar and fairly substantial material around it but it's the single bar that has me nervous.clengman wrote:This is the lens spanner I was looking at.
https://rover.ebay.com/rover/0/0/0?mpre ... 1303732469
It would be nice to get inside of 8mm too. The pin bolts on the back of the arm on the series 2/4 are 6mm span and it you ever have to get into the arm to lube or service the focusers, those have to come out. They can be tight too.
Re: AO Series 4 illuminator cleaning tips?
I think I'll take a chance with the cheap spanner. It's in my budget right now. I'll figure something out if I have to lube the stage.
Checked illuminator alignment. It seems like it's not great. When mirror is on plane, field iris image is shifted maybe a third of the way over towards the right of the field of view. I can push on the condenser and get it close to centered, but it just drifts back to the right as I use the scope. Not sure there's going to be a solution to that short of buying a centerable condenser. Since I can't seem to do both, I'm not sure if it's better to have the field iris image centered or to have the mirror on plane...
On a more positive note, my daughter and I took a sample from one of our potted plants. We both got to see our first live paramecium. Pretty cool! I looked at another drop of water after she went to bed. Found another paramecium, several euglena, and a vorticella. I'm having a good time with it!
Checked illuminator alignment. It seems like it's not great. When mirror is on plane, field iris image is shifted maybe a third of the way over towards the right of the field of view. I can push on the condenser and get it close to centered, but it just drifts back to the right as I use the scope. Not sure there's going to be a solution to that short of buying a centerable condenser. Since I can't seem to do both, I'm not sure if it's better to have the field iris image centered or to have the mirror on plane...
On a more positive note, my daughter and I took a sample from one of our potted plants. We both got to see our first live paramecium. Pretty cool! I looked at another drop of water after she went to bed. Found another paramecium, several euglena, and a vorticella. I'm having a good time with it!
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
yes but all the double rail ones are about the same price or even cheaper.clengman wrote:I think I'll take a chance with the cheap spanner. It's in my budget right now. I'll figure something out if I have to lube the stage.
Checked illuminator alignment. It seems like it's not great. When mirror is on plane, field iris image is shifted maybe a third of the way over towards the right of the field of view. I can push on the condenser and get it close to centered, but it just drifts back to the right as I use the scope. Not sure there's going to be a solution to that short of buying a centerable condenser. Since I can't seem to do both, I'm not sure if it's better to have the field iris image centered or to have the mirror on plane...
On a more positive note, my daughter and I took a sample from one of our potted plants. We both got to see our first live paramecium. Pretty cool! I looked at another drop of water after she went to bed. Found another paramecium, several euglena, and a vorticella. I'm having a good time with it!
Re: AO Series 4 illuminator cleaning tips?
So, I got the spanner in the mail yesterday and have begun my program of dust hunting. I decided to start from the top down. EPs are pretty good now. I unscrewed the eyepiece tubes, cleaned the windows sealing the top of the bino head. Then I was dismayed to see that there is a big ol' fingerprint on one of the prisms. I removed the trinocular tube and it's mounting flange to try to get a better look inside. I can see that there are two prisms, one mounted to the slider by a clip and some adhesive and a second that I assume splits the light path to the two eyepiece tubes. I couldn't see yet how that one is mounted. I can't tell which surface of which prism is actually carrying the smudge. Once again I don't want to just start taking things out and risk messing up some alignment that I won't be able to easily restore. What's a good starting point to figure out which surface needs to be cleaned? Will I even be able to clean the prisms without unmounting them? How difficult is realignment after they have been removed. Thanks!
Carl
Carl
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
unusual to have a fingerprint on a prism surface inside the head. is it possible it is on the optical window, in the bottom of the head?
Re: AO Series 4 illuminator cleaning tips?
Yes. I'm sure. Shining a light in through that window in the dovetail, I can see that both surfaces of the window are clean and the smudge is inside on the surface of the prism. I can see the smudge looking in through the eyepiece tubes as well, so it's a little difficult to tell exactly where it is on the prisms, but I'm pretty sure it's on the bottom surface of the lower prism. Thought maybe I could just remove the dovetail from the bino head and get to it that way, but it seems like the slider is attached to the dovetail on the inside.apochronaut wrote:unusual to have a fingerprint on a prism surface inside the head. is it possible it is on the optical window, in the bottom of the head?
Re: AO Series 4 illuminator cleaning tips?
Found it. It was on the rear surface of the prism splitting light path to the two EP tubes. Unscrewed the front of the bino head from the body and found it right away.
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apochronaut
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Re: AO Series 4 illuminator cleaning tips?
somebody incompetent was messing around with that.
Re: AO Series 4 illuminator cleaning tips?
Now two people who are incompetent have been messing around with it. 
I'm trying to improve my competence, though.
I had some time last night so I finally got around to opening up the illuminator to give it a good cleaning. The collector lens, the mirror and the window on the field diaphragm (inside and out) were pretty filthy. They are much better now. A few unexpected things made it a little bit of an adventure. I removed the entire optical assembly for the illuminator as you suggested, Apo. Then I separated the rear part of the assembly so I could get at the inside of that window on the field diaphragm iris. I was not expecting the mechanism of the iris to be so exposed at that point, but I have encountered mechanisms like this before, having cleaned and lubed the shutter on an Agfa folding camera. I did my best not to disturb the mechanism while I cleaned the inside of the window. I probably should have put the assembly back together before prying off the retaining ring behind the frosted glass lens on the rear of the illuminator. I got the lenses out of the back, still taking care with the iris leaves on the front. I cleaned them well, reassembled, pressed the retaining ring back into place, but when I turned it over again, I had a leaf from the iris that had somehow gotten loose from the rest of them.
It took a lot of fiddling to get it back into place, but I did eventually. Unfortunately during all the fiddling with the iris I must have knocked loose a little more dust. I'm going to have to open the illuminator again at some point. Dust on those lenses inside the illuminator housing is pretty obvious in the field of view, but at least there's less of it now than there was previously.
All in all I think it was a useful if not 100% successful operation. I'd say I got rid of 85% of the dust and smudges that were interfering with my image quality, but I'm glad I have some familiarity now with all the inner workings. I'll be a little more confident and quicker and hopefully more thorough the next time I go back in.
I'm trying to improve my competence, though.I had some time last night so I finally got around to opening up the illuminator to give it a good cleaning. The collector lens, the mirror and the window on the field diaphragm (inside and out) were pretty filthy. They are much better now. A few unexpected things made it a little bit of an adventure. I removed the entire optical assembly for the illuminator as you suggested, Apo. Then I separated the rear part of the assembly so I could get at the inside of that window on the field diaphragm iris. I was not expecting the mechanism of the iris to be so exposed at that point, but I have encountered mechanisms like this before, having cleaned and lubed the shutter on an Agfa folding camera. I did my best not to disturb the mechanism while I cleaned the inside of the window. I probably should have put the assembly back together before prying off the retaining ring behind the frosted glass lens on the rear of the illuminator. I got the lenses out of the back, still taking care with the iris leaves on the front. I cleaned them well, reassembled, pressed the retaining ring back into place, but when I turned it over again, I had a leaf from the iris that had somehow gotten loose from the rest of them.
It took a lot of fiddling to get it back into place, but I did eventually. Unfortunately during all the fiddling with the iris I must have knocked loose a little more dust. I'm going to have to open the illuminator again at some point. Dust on those lenses inside the illuminator housing is pretty obvious in the field of view, but at least there's less of it now than there was previously. All in all I think it was a useful if not 100% successful operation. I'd say I got rid of 85% of the dust and smudges that were interfering with my image quality, but I'm glad I have some familiarity now with all the inner workings. I'll be a little more confident and quicker and hopefully more thorough the next time I go back in.
Re: AO Series 4 illuminator cleaning tips?
I like to read these detailed posts about microscope repair, although my scope is different. My own constant worry when doing mechanical jobs is to disrupt optical alignment. When other microscopists succeed, there is hope.